Flexible coupling



llg- 30, 1960 A. M. GooDLoE FLEXIBLE COUPLING Filed Sept. l5, 1959 y filial IN VENTOR.

A T TOR NEV FLEXIBLE CGUPLING Alfred Minor Goodloe, Westlield, NJ., assigner to Metal Textile Corporation, Roselle, NJ., a corporation et Delaware Filed Sept. 15, 1959, Ser. No. 840,092

10 Claims. (Cl. 64-15) This invention relates to ilexible coupling structures and to methods of making them. The invention relates more particularly to a exible coupling structure made from a tubular element having spring Wires, some of which form right-hand helixes and others of which form left-hand helixes, the helixes of opposite lay being interlaced, that is, the wires of the right-hand helixes passing alternately over and under the wires `of the left-hand helixes, and the tubular element being bulged.

lt is an object of the invention to provide an improved flexible coupling for transmitting torque between rotatable elements regardless of axial misalignment, angular misalignment and variations in axial spacing of the elements between which the torque is to be transmitted. The invention is intended primarily for transmitting light torque from small motors and for transmitting torque from manually operated knobs or other elements to instrument control devices.

Another object of the invention is to provide an improved method for making iiexible couplings of the character indicated.

Although intended for a coupling to transmit torque, the coupling of this invention can be used for other purposes, such as special spring installations and for vibration damping. Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

in the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the view:

Figure 1 is a view of a portion of a flexible tubular element from which the couplings of this invention are made;

Figure 2 is a view showing the way in which the tubular element is pulled down to a small diameter and assembled with wires for making the flexible coupling;

Figure 3 is a View, mostly in section, showing a ilexible coupling made in accordance with this invention;

Figure 4 is a View similar to Figure 3 but showing the end fittings of the flexible coupling in axial misalignment;

Figure 5 is a view, partly in section, showing a modied form of the invention with the end fittings in angular misalignment;

Figure 6 is a view similar to Figure 3 but illustrating the operation of the coupling when the axial `spacing of the end fittings is reduced; and

Figure 7 is a greatly enlarged fragmentary View illustrating the relation of the spring wires in a construction using double wires.

Figure l shows a iiexible element 10 consisting of a tube formed of spring wires 12 and 14. Those wires designated by the reference character 12 form righthand helixes, and the wires designated by the reference character 14 form 4left-hand helixes. The wires 12 are spaced from one another, and the wires 14 are also spaced from one another; but the wires of opposite lay are interlaced, that is, the wires of the right-hand helixes pass alternately over and under wires of the left-hand helixes.

2,950,509 Patented Aug. 3Q, 1960 Ihis construction of the flexible element or tube 10 provides an open construction with interstices of substantial cross section between wires 12 and 14. and the wires are made of spring material so that the element or tube 10 can be bent and will return to its original condition within limits. The spr-ing wires, however, are not hard enough to break, even though bent quite sharply.

Figure 2 shows a step in the method of making the flexible coupling of this invention. The tubular element 10 is drawn out to an increased length by a strong axial pull, and through a die, if necessary. This operation reduces the diameter of the tube 10 so that all of the wires are close to the longitudinal axis of the tube. ri`wo eyelets 16 are threaded over the thinned-down tube 10. Each of the eyelets has a flange i8 and the eyelets are placed on the tube 10 with the anges 18 confronting one another. The eyelets are spaced axially on the tube 1G with sutlcient length of the tube between them to supply the material necessary for a particular coupling. The tube is then cut at upper and lower lines 20. The portions of the tube 10 within the eyelets 16 are then secured to the eyelets by solder 22. In the broader aspects of the invention, this solder 22 is merely representative of means for securing the eyelets to the ends of the cut length of the tube 10.

The eyelets are then urged together along the axis of the tube it) and this causes the free length of the tube to form a bulge 25, as shown in Figure 3. The eyelets are pushed close together so that the wires are bent beyond their elastic limits, and when the axial end pressure is released, the wires of the tube l0 spring back to a bulged position, such as shown in Figure 4.

The wires in the bulge 26 are still in their helical form, the terms helical and helix being used herein to designate a course in which a wire follows a combined axial and circumferential path but without being limited to a uniform radius for the circular path. For example, the radius of each helix in the bulge 26 increases progressively to a maximum at a mid region of the bulge and then decreases to a substantially smaller radius at the end of the bulge.

The eyelets 16 are used to connect the coupling to end iittings 28, to which the eyelets are soldered or otherwise secured. In the construction illustrated, the end fitting 2S threads into a flange 30 by which the coupling is connected to an actuator or to a part which is to be turned by torque transmitted through the coupling.

Figure 4 shows the upper end iitting 28 with its axis parallel to that of the lower end iitting 28, but these axes are oset from one another. This causes a distortion of the bulge 26 and requires some bending of the wires as the bulge rotates during transmission of torque from one end iitting to the other.

Figure 5 shows -a modied construction in which the upper end tting 28 extends through a iixed panel 34. A manually-operated knob or `actuator 36 threads over the outer part of the end litting 28 and is locked to the end iitting by a lock nut 3S which fits the same threads 40 as hold the actuator 36. A washer 42 bears against the front of the panel 34. The lower end iitting 2S connects with an element of a controller which is to be adjusted from the knob or actuator 36.

ln Figure 5 the upper and lower end ttings 23 are in axial misalignment, and the bulge 26 is distorted in a somewhat different way than in Figure 4, the wires being bent more sharply on one `side than on the other. The bulge 26 will transmit torque, however, with axial misalignments approaching even though the misalignment changes from time to time with change of temperature, or is constantly changing as a result of a vibration 3 mounting for the instrument to which torque is transmitted by the lower end fitting 28.

The flexible coupling of this invention can be used for Ytransmitting torque between rotary elements which, have both axial misalignment, as in Figure 4, angular misalignmen-t, as in Figure 5. Y r

VFigure 6 shows the way in'which the bulge is distorted to a shorter axial length and greater maximum'diameter when the axial spacing of the end iittings 28rbecomes less. Conversely, the bulge 26 will elongate fand its maximum diameter will become less as the end fittings 28 move apart axially. A It is one of the advantages of this invention that it operates equally wellV in spite of changes in the axial spacing of the end littings 28 withinvery wide For example, the end iittings can move closer together until they almost contact one another, though actual contact is Vimpossible because ofthe spring wires in the bulge 26. vAs the end iittings move apart in an axial direction, thediameter of the bulge 26 may decrease until it approaches that of the portions of the tube within theeyelets 16. It the bulge isY entirely lost, however, as a result of increased axial length of the coupling, the

4 structure having end fittings spaced from one another axially along the length of the tubular element, and the tubular element between the end fittings being bulged so that the helixes increase in diameter from each end fitting to an intermediate region between the ttings where the helixes are of a maximum diameter.

2. The coupling structure Adescribed in claim l and in which the wiresnare springy and return to their original shape when thehelixes are distorted by rotation of the bulge with the axes of the end Viittings misaligned with oneanother. 4 Y' 3. The coupling structure described in claim 2 and in which the wires are round steel wires.

4. The coupling structure described in claim 2 and in which each of the wiresY is' amulti-st'rnd wire for increasing the flexibility of a coupling of a given strength.

5. The coupling structure described in claim 1 and in which the portions of vthe tube Awithin the vend ttings are strength of the coupling is greatly impaired and the improved operation of the coupling, as compared with ordinary springs, is largely lost. Y Y

The wires used for the coupling Vare preferably round wires made of steel, but yother kinds of wire can be used. Steel has the advantage of good spring quality over a wide range. Beryllium copper is also used and other materials which have good spring effect. The size and the number ofwrires employed in the tube may be Varied. Small kWires provide a more flexible coupling than larger wires ofthe same material. The choice of wire size and material depends upon the use `for which the coupling is intended. f

Figure 7 shows a construction in which double wires are used vfor Ythe tube 10. Each of the wires 12 consists of two strands side-by-side; and Figure 7 also shows the Way in vwhich a double-strand wire 14 passes under the ilirst of the double-strand Wires 12 and then passes over the next ofthe double-strand wires 12'. This construction is repeated around the entire circumference of the tube. r

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some featuresmay be used in diierent combinations without departing fm the invention as deiined inthe claims; f Y

What is claimed is: H z. u1;A coupling structure including a exible tubular element made of Yspring wires, some of the wires form-y ing right-handihelixes and other wires forming left-hand helixes, the Wires of opposite lay being interlaced so that each wire of the right-hand helixes passes alternately over and under Wires of the left-hand helixes, the coupling I radially compressedso that the wires within each of the end ttings are in Aclose proximity Withoneyanother.

6. 'Ihe coupling structure describedinclaim 5 rand in which the interstices between the wires in the end ttings iare fllled with solder. Y Y l j 7. The coupling structure described in claim 1 and in which all of the wires in each of the end fittings ,are bonded to the end fittings Vas a unitary structure.

r 8. Amethod of making a exible coupling from a tube made of spring wire with the Wires forming interlaced right and left-hand helixes, which method comprises placing'end ttings over the tube, securing `the end ttings to the tube in axially-spaced locations, and compressing the y,tubejaxially until the portion of the tube between the end ittings bulges to a diameter substantiallylarger than` at the end ttings and with progressing decreases in the diameter of the bulge in the direction of the end fittings.

9, The methodY of l making a exible coupling as described in claim 8 and in which the end'ittings are applied j: to a long length'V of tube, 4and the tube is cut oit at an end iitting before being bulged, and in which the -tube is secured to the end ttings by bonding the wire of the tube to the Ysurrounding surfaces of the end iitting.

10. The method of making a flexible coupling, as described in claim 8, and in which the tube is rst drawn Duc Apr. 28, 1891 1,602,022 Hetland Oct. 5, 1926 2,047,329 l Peterson July 14, 1936 2,352,391 Kitselrnan June 27, 1944 

